Psychologists have confirmed commonplace intuitions about the significant limitations that people have with remembering items and events. These limitations become apparent when people attempt to retrieve information such as during a search for previously seen information using common search tools such as a web browser.
Most information retrieval tools, like popular web or intranet search engines, are designed to facilitate information discovery. However, much knowledge work involves integration and reuse of information that has previously been created, found or received. For example, creating a presentation or paper may involve pulling together information from existing information sources like presentations, documents, spreadsheets, data analyses, email messages, and so forth. Studies have shown that a large percentage of web pages accessed were re-visits to pages previously seen. Similar re-access patterns have been observed in retrieving information from technical manuals, Unix commands, book borrowing, and human memory, for example.